The invention is relates generally to a windshield wiper having a wiper arm, which is driven via a drive shaft and to which a wiper blade is pivotably connected.
Known windshield wipers have a wiper arm, which is made up of a fastening element and a hinge element, which is pivotably connected to it via a swivel joint and has a wiper rod. A hooklike end of the wiper rod engages a suspension box of a wiper blade, which is formed by two side cheeks of a middle bracket and includes a hinge bolt. The hinge thus formed guides the wiper blade over the vehicle window during the swiveling motion. The wiper blade has what is as a rule a multi-member support bracket system, with subordinate brackets pivotably connected to the middle bracket, at least some of which subordinate brackets, with claws on their ends, retain a wiper strip by its head strip. The multi-member support bracket system and spring rails placed in the head strip make it possible during wiping for the wiper strip to adapt, with a uniform contact pressure, to a curved windshield. To that end, a tension spring prestresses the swivel joint. The wiper arm is secured with its fastening element on a drive shaft and is driven by it in the wiping motion. Such windshield wipers are known, for instance from German Patent Disclosure DE 37 44 237 A1. In simple versions, subordinate brackets, also known as intermediate brackets and claw brackets, can be dispensed with. In the simplest case, the middle bracket itself has claws, with which it retains the wiper strip.
Windshield washing systems for vehicles are as a rule used in conjunction with windshield wipers. They are actuated if the moisture from precipitation does not suffice to clean the vehicle window. They include a water container, spray nozzles, and a pump which pumps water, sometimes admixed with cleaning and antifreeze agents, under pressure out of the water container to the spray nozzles. As a rule, the spray nozzles are secured to some part of a vehicle body, such as a hood, window frame, or the like. To prevent the spray nozzles from freezing at temperatures below the freezing point, heating elements are integrated into the spray nozzles and communicate with a power supply via plugs located on the outside. The heating elements require relatively great effort and expense for producing the spray nozzles and great effort and expense for assembly for laying the electric lines and contacting the plugs. Furthermore, the highly volatile antifreeze agents rapidly evaporate, and the nozzle openings become plugged with the residues.
It is already known to secure spray nozzles as additional components on the wiper blade and thus to distribute the spraying water over the wiping region directly with a short stream length. Since the spraying water is concentrated on a region in the vicinity of the wiper blade and is wiped off again in the briefest time by the wiping motion, the view is hindered only briefly by the spraying water applied. A disadvantage of such systems is that the effects of weather, especially hail and extreme sunshine, have a major effect on the flexible parts of this arrangement, which are required for spanning the jointed regions between the wiper arm and the wiper blade. The spray nozzles and water lines that are exposed to the relative wind also freeze up quickly at temperatures below the freezing point, unless enough antifreeze is added to the water. As a rule, thawing the frozen water lines and spray nozzles again can be done only with major effort.
In an earlier German patent application, DE 198 15 171.3, a wiper arm is described, on whose hinge element, or on a wiper rod integrally joined to the hinge element, spray nozzles are disposed. These nozzles have a nozzle body, which is accommodated in a bulge of the hinge element with an opening for the spray stream, or is clipped, protruding downward, in a lateral mount on the wiper rod. It is also possible for two nozzle bodies to be provided, which are joined together by a rigid or flexible connecting piece. The nozzle bodies can be replaced easily and are well protected against environmental factors.
Expediently, the spray nozzle has an outward-opening check valve, which prevents the water line from running empty if the washer system goes unused for relatively long periods, or if water escapes during wiping operation without any washing function, especially at high wiping frequencies and/or with stroke-controlled wiper arms. Furthermore, washing water and antifreeze is prevented from evaporating in the region of the spray nozzle, especially in the case of a heated spray nozzle, and narrowing or plugging up the spray nozzle with deposits.
A heater which is passed in the form of a wire through a water supply lead and is embodied as a heating coil in the nozzle body is integrated with the wiper system. The heater fits only one type of windshield wipers, so that a large number of different heating devices must be kept in stock. Furthermore, there are simple versions in which the nozzle bodies are integrally joined together and produced as a plastic injection-molded part. By means of the nozzle bodies distributed on the wiper arm, the spraying water is well distributed over the wiper region, especially if a spray stream is aimed at a lower region directly in front of the wiper blade. Since short stream lengths result from this arrangement, even at relatively high vehicle speed the relative wind can have only little effect on the distribution of spraying water.